Method for controlling data transmissions on a single channel radio frequency network

• US 5,493,722 A
• Filed: 01/24/1994
• Issued: 02/20/1996
• Est. Priority Date: 01/24/1994
• Status: Expired due to Term

• Current Assignee: Clark Equipment Company (Doosan Enerbility Company Limited)
• Original Assignee: Ingersoll-Rand Company (Trane Technologies plc)
• Inventors: Pritchard, David R., Gunn, John T.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): VO, NGUYEN THANH
• Application Number:
  US08/185,740
• Time in Patent Office: 757 Days
• Field of Search: 455/88, 455/54.1, 455/67.1, 455/56.1, 455/66, 455/49.1, 455/53.1, 455/68, 455/70, 370/85.2, 370/85.3, 370/85.1, 370/95.2, 340/853.8, 340/854.6, 340/856.2, 340/870.11, 340/870.15, 340/825.54, 340/855.4, 340/855.5, 340/870.16, 340/870.01, 340/870.04, 342/50, 342/51
• US Class Current: 455/517
• CPC Class Codes: H04B 7/00 Radio transmission systems, i.e. using radiation field H04B10/00, H04B15/00 take precedence
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 74/004 in the uplink, i.e. towards network
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal

Abstract

A site system for remotely monitoring and controlling portable machines is provided which includes a single channel radio frequency network. At least one portable machine has a microcontroller for controlling operation of the portable machine, a plurality of sensors for supplying machine operational data to the microcontroller, and a radio frequency transceiver unit. The radio frequency transceiver unit communicates with the microcontroller, and with the single channel radio frequency network. At least one host computer has a radio frequency transceiver unit. The host computer communicates with a predetermined portable machine by data transmissions on the single channel radio frequency network. A radio frequency protocol controls radio frequency data transmissions on the single channel radio frequency network.

Claims

1. A method for controlling data transmissions on a single channel radio frequency network which is arranged to permit data transmissions in a system for remotely monitoring and controlling portable machines, the system including a plurality of nodes comprising at least one portable machine having a microcontroller for controlling operation of the portable machine, a plurality of sensors for supplying machine operational data to the microcontroller, and a radio frequency transceiver unit which communicates with the microcontroller, and at least one host computer having a radio frequency transceiver unit;

all nodes on the network having the same status and privileges, each being able to originate and receive communications;

each node independently performing the same method comprising the steps

initializing each node upon power up the initializing comprising setting a CTSFLAG to zero and setting a CTS timer and a RTS timer each to a predetermined value and initiating the CTS timer;

detecting an appropriate message during a predetermined interval of time, the message having a unique structure, and if the appropriate message is received;

checking the message for a request to send command, and if the send command request exists, setting the CTSFLAG to zero and starting the CTS timer, and if the send command does not exist;

checking the message for a clear to send command, and if the clear to send command is exists, setting the CTSFLAG to a one and if the clear to send command does not exist;

checking the message for an application command, and if the application command exists, responding to the originating node of the command;

upon not detecting an appropriate message, continuing to scan for an appropriate message;

determining a present need to transmit a message to a predetermined node;

checking the value of the CTSFLAG and if it is zero, checking to see if the CTS timer has expired;

if the CTS timer has expired, simultaneously transmitting a message having a request to send command to all nodes on the network and starting the RTS timer;

transmitting an appropriate application message to the predetermined node on the network;

waiting for an appropriate response from the predetermined node on the network, and if an appropriate response is not detected from said node, incrementing a loop counter and waiting a predetermined time interval to re-transmit the application message;

after an appropriate response is detected from the predetermined node, determining if the time interval of the RTS timer has expired, and if it has expired, transmitting a clear to send message to all nodes on the network and setting the CTSFLAG to one; and

if the RTS timer has not expired, transmitting additional application messages during the time interval of the RTS timer.

2. A method for controlling data transmissions on a single channel radio frequency network, as claimed in claim 1, and wherein the CTS timer times an interval of time during which a clear to send command is detected.

3. A method for controlling data transmissions on a single channel radio frequency network, as claimed in claim 1, and wherein the appropriate message has a message structure comprising a STX field, a destination address field, an origin address field, a command field, a data field length, a data field and a check sum field.

4. A method for controlling data transmissions on a single channel radio frequency network, as claimed in claim 3, and wherein the predetermined time interval for waiting to retransmit is determined by determining a value of the transmitting node'"'"'s origin address and multiplying said value by a loopcount, to obtain a number, and multiplying said number by a predetermined constant.